The tri-post insulator is a core component within the gas-insulated transmission lines(GIL),providing both electrical insulation and mechanical support.Typically,it is high-temperature cured through vacuum casting of ...The tri-post insulator is a core component within the gas-insulated transmission lines(GIL),providing both electrical insulation and mechanical support.Typically,it is high-temperature cured through vacuum casting of a mixture of epoxy resin,curing agent,and alumina fillers.In recent years,frequent incidents of mechanical cracking and breakdown of tri-post insulators have been reported,which are attributed to residual stress concentration.However,the formation mechanism and distribution characteristics of the residual stress remain unclear.This study focuses on the curing kinetics and re-sidual stress modelling of GIL tri-post insulators.It is verified that the epoxy resin/alumina reaction system follows the autocatalytic curing kinetic model by differential scanning calorimetry tests,and the model fitted by Malek's method corresponds well with the experimental results.Based on the Cure Hardening Instantaneously Linear Elastic model and the density inhomogeneity,it is found that a tensile stress concentration with a maximum value of 58.9 MPa at the edge of the insulator/sleeve interface,due to the mismatch of chemical and thermal shrinkage effects.Besides,the filler sedimentation can decrease the coefficient of thermal expansion and suppress the residual stress concen-tration.The investigation would help with the visualisation of the residual stress distri-bution in GIL tri-post insulators and provide some guidance for their processing treatments.展开更多
The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate particles.The way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis...The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate particles.The way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous work.However,the thickness of the modulating electrode is neglected.In practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles reduces.In this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to particles.The results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating electrode.First,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing effect.Second,the range of regulating channel flux to achieve the optimal separation is extended.Third,the separation efficiency improves since the perfect separation can be achieved at a higher flow rate.Furthermore,the effects of the location and the size of the insulating post on particle separation are analyzed in detail.The present work could provide the reference for the application of the DEP technology.展开更多
基金National Science and Technology Major Project,Grant/Award Number:2024ZD0802403National Natural Science Foundation of China,Grant/Award Number:52377153Measurement and Technology Key Project of Tianjin City,Grant/Award Number:2024TJMT011。
文摘The tri-post insulator is a core component within the gas-insulated transmission lines(GIL),providing both electrical insulation and mechanical support.Typically,it is high-temperature cured through vacuum casting of a mixture of epoxy resin,curing agent,and alumina fillers.In recent years,frequent incidents of mechanical cracking and breakdown of tri-post insulators have been reported,which are attributed to residual stress concentration.However,the formation mechanism and distribution characteristics of the residual stress remain unclear.This study focuses on the curing kinetics and re-sidual stress modelling of GIL tri-post insulators.It is verified that the epoxy resin/alumina reaction system follows the autocatalytic curing kinetic model by differential scanning calorimetry tests,and the model fitted by Malek's method corresponds well with the experimental results.Based on the Cure Hardening Instantaneously Linear Elastic model and the density inhomogeneity,it is found that a tensile stress concentration with a maximum value of 58.9 MPa at the edge of the insulator/sleeve interface,due to the mismatch of chemical and thermal shrinkage effects.Besides,the filler sedimentation can decrease the coefficient of thermal expansion and suppress the residual stress concen-tration.The investigation would help with the visualisation of the residual stress distri-bution in GIL tri-post insulators and provide some guidance for their processing treatments.
基金Project supported by the National Natural Science Foundation of China(No.11572139)。
文摘The dielectrophoretic technology has been one of the most frequently applied microfluidic technologies to manipulate particles.The way of a combination of controlled electroosmotic micro-vortices and dielectrophoresis to manipulate particles of different sizes was proposed in our previous work.However,the thickness of the modulating electrode is neglected.In practice,when the thickness of the modulating electrode increases,the channel flux increases,while the ability of the vortex to capture the particles reduces.In this study,a new method combining the field-modulating electroosmotic vortex and the insulating post is proposed to improve the manipulating capability of the field-modulated electroosmotic vortex to particles.The results indicate that there are three great advantages as the insulating post is placed on the channel wall on the same side of the modulating electrode.First,the capturing ability of the vortex to particles is greater due to the reduction of channel flux and the squeezing effect.Second,the range of regulating channel flux to achieve the optimal separation is extended.Third,the separation efficiency improves since the perfect separation can be achieved at a higher flow rate.Furthermore,the effects of the location and the size of the insulating post on particle separation are analyzed in detail.The present work could provide the reference for the application of the DEP technology.
